Hydrotreating lubricating oil to improve color and neutralization number using a platinum catalyst on alumina



July 24, 1956 w. T. KNOX, JR

HYDROTREATING LUBRICATING OIL TO IMPROVE COLOR AND NEUTRALIZATION NUMBER USING A PLATINUM CATALYST ON ALUMINA Filed May 13. 1952 vuum I uenwmhmka uuawoan mug-83; :|w w H H A A UW 0 o R N NH 2 |.Nl 5 5m ohvbi 1 W H W. 25. I

Wiuiam T Knox Jr. e7Inventor Q5820, W Qttorneg United States Patent HYDROTREATING LUBRICATING OIL TO IM- PROVE COLOR AND NEUTRALIZATION NUM- BER USING A PLATINUM CATALYST ON ALU- MINA William T. Knox, Jr., Cranford, N. J., assignor to Esso Research and Engineering Company, a corporation of Delaware Application May 13, 1952,.SerialNo. 287,523

3 Claims. (Cl. 196-35) The present invention is concerned with a process for the hydrofining of hydrocarbons boiling in the lubricating oil boiling range. The invention is more particularly concerned with the use of a platinum catalyst utilizing .mild hydrofining conditions. In accordance with the present invention, improved lubricating oil products are secured by mildly hydrofining hydrocarbons boiling in the lubricating oil boiling range utilizing a platinum catalyst. In accordance with the present process the hydrogen consumption is maintained below about 150 cu. .ft. per ban rel at standard conditions, preferably below about 75 cu. ft. per barrel.

It is well known inthe art to carry out various operations wherein hydrogen is employed for the treatment of various petroleum oil fractions. These operations are normally carried out for various purposes such as desulfurization. In processes of this character temperature, pressure, and other operating conditions are adjusted whereby a relatively high consumption of hydrogen per barrel of feed is secured. The hydrogen consumption is normally in the range from about 200 to 600 cu. ft. and higher per barrel of oil feed.

It has now been discovered that a high quality lubricating oil product can be obtained providing hydrocarbons boiling in the lubricating oil boiling range are subjected to mild hydrofining conditions. The color of the lubricating oil is materially improved as well as its neutralization number. Normally, it is considered that a satisfactory lubricating oil should have a neutralization number not in excess of about 0.1 (acidity as measured in mg. KOH per gr. oil).

The neutralization number is an indication of the quantity of acidic materials present, usually naphthenic acids and related compounds. The naphthenic acids are very undesirable in a lubricating oil since under operating conditions of high temperatures and pressures they tend to cause excessive corrosion and sludging in the engine. Manufacturing experience has shown that a high viscosity index is not required in many lubricating oils if other properties are provided. For instance, when solvent extracting lube distillate fractions secured from coastal crudes boiling in the lubricating oil boiling range with phenol to a viscosity index of 60, the neutralization number is reduced to only about .2. This is not a satisfactory lubricating oil product as regards neutralization number and viscosity index is higher than required. The lubricat ing feed oils from these sources have initial neutralization numbers of about .7 and above.

Usually, if a lubricating oil product has a satisfactory color, and a neutralization number below about 0.1, a viscosity index of about 50 is entirely satisfactory. Thus, the

present invention is particularly adapted for the processing of lubricating oil feed fractions which have neutralization numbers above about 0.5, particularly above about 0.7.

The process of the present invention may be more fully understood by the drawing illustrating one embodiment of the same. Referring specifically to the drawing, a .feed oil comprising lubricating oil constituents is introduced into distillation zone 1 by means of feed line 2. Temperature and pressure conditions are adjusted in zone 1 to remove overhead by means of line 3, normally gaseous hydrocarbons. Hydrocarbons boiling in the motor fuel boiling range are removed by means of line 4 while gas oil constituentsare removed by means of line 5 and passed to a cracking zone. A residuum fraction is removed by means of line 6 while a hydrocarbon fraction boiling in the lubricating .oil boiling range (about 700 F. to 1l00 F. at 760 mm. pressure) is removed by means of line 7. In accordance with the present invention, this lubricating oil fraction is passed into zone 8 wherein temperature and pressure and other operating conditions are adjusted to secure a mild hydrofining operation, which will be hereinafter described.

The hydrofined product is withdrawn from zone '8 by means of line 9, passed through a cooling zone 10 and then introduced into a hydrogen separation zone 11. Hydrogen is removed overhead from separation zone 11 by means of line 12, recompressed in compressor zone 13 and then preferably recycled to Zone 8 by means of line 14 with the fresh hydrogen feed which is introduced into zone 8 by means of line 15. Y

The refined product free of hydrogen is removed from the bottom of zone 11 by means of line 16 and introduced into .a separation zone 17. Temperature and pressureconditions in zone 17 are adapted to remove overhead by means of line 18 hydrogen sulfide and any light or .low boiling hydrocarbons. Steam may be introduced into zone 17 by means of line 19. A hydrofined lubricating oil product of a low neutralization number, below about 0.1 and having a satisfactory color, is withdrawn from zone 17 by means of line 20.

The present invention is broadly concerned with the mild hydrofining of hydrocarbon oil fractions boiling in the lubricating oil boiling range. These oils are normally virgin distillates having viscosities at 100 F. in the range from about 100 to 1000 Saybolt seconds, viscosity indexes in the range from about 50 to 50 and boil above about 700 F. at 760 mm. pressure. Usually these oils boil in the range from about 700 F. to 1100 F. at 760 .mm. pressure.

The catalyst comprises a platinum catalyst supported on a solid carrier. The carrier preferably comprises alumina or silica gel. The amount of catalyst by weight based upon the carrier such as alumina is in the range from about .05 to 1.0%. One method of preparing the catalyst is to activate a carrier such as alumina by calcining the same. The alumina .is then impregnated with an aqueous solution of chlor platinic acid to secure a paste. The impregnated alumina is then dried at a temperature in the range from about room temperature to 250 F. The dried material is then calcined very slowly wherein the temperature is raised from about 50 to per hour ing oil fraction is mildly hydrofined. The hydrofined lubricating oil after removal from the hydrofining zone may be further treated to remove small traces of dissolved hydrogen sulfide. Thus, the hydrofined lube oil may be caustic-washed. These undesirable constituents on the other hand may be removed from the mildly hydrofined heating oil by steam stripping or by an equivalent treating process.

It is essential in practicing the present invention that the hydrofining operation conducted on the lubricating oil be a mild hydrofining operation utilizing a platinum catalyst preferably supported on alumina. This is to be distinguished from conventional hydrofining operations heretofore practiced in the art. Such hydrofining operations previously employed have utilized pressures in the range from about 200 to 500 lbs. p. s. i. at feed rates of .5 to 2.0 volumes of feed per volume of catalyst per hour. Relatively high rates of hydrogen recycle have been employed, as for example, 2,000 to 4,000 standard cu. ft. per barrel in order to prevent carbonization of the catalyst. Likewise, very active catalysts have been used which are effective for desulfurization. Under these conditions by drogen consumption has generally been in the range of 200 to 600 standard cu. ft. per barrel of feed. This relatively high consumption of hydrogen in the past has made the process expensiveto operate, so that its application in the past has been limited to the treatment of relatively high sulfur stocks which could not be desulfurized by any other available treating operation. The catalyst heretofore employed has been a cobalt molybdate supported on a carrier, as for example alumina.

The mild hydrofining conditions of the present invention may be secured by lowering the temperature, increasing the feed rate per volume of catalyst or by using a less active catalyst. In accordance with the present invention the temperatures used are in the range from about 400 to 700 F., preferably in the range from about 600 F. to 700 F. Pressures employed are in the range from about 50 to 250 lbs. per sq. in., preferably in the range from about 100 to 200 lbs. per sq. in. The feed rates, in accordance with the present process, are in the range from about .5 to 5 volumes of liquid per volume of catalyst per hour. Preferred feed rates are in the range from 1 to 2 v./v. hr. The hydrogen in the gas to the hydrofining unit may vary from 50 to 100%. This means that, for example, dilute hydrogen from a hydroformer can be used in the hydrofining process.

It is to be understood that the mild hydrofining conditions of the present invention are secured by the interadjustment of the above enumerated operating conditions. For instance, if a relatively high liquid feed rate is used as compared to the amount of catalyst present, the higher temperature range may be employed. The mild hydrofining conditions of the present invention are measured by the amount of hydrogen consumption per barrel of oil feed. As pointed out heretofore in the art, conventional hydrofining operations utilized for the desulfurization of certain stocks are conducted under conditions whereby the hydrogen consumption ranges from 200 to 600 standard cu. ft. of hydrogen per barrel of oil. These operations used heretofore in the art secured a substantial sulfur reduction (50 to 90%). In accordance with the present. process, operating conditions are adjusted so that the hydrogen consumption in standard cu. ft. per barrel does not exceed 150 and is preferably less than 75 cu. ft. per barrel. Furthermore, the extent of the sulfur reduction when utilizing the mild hydrofining conditions of the present invention does not exceed about 35% and preferably does not exceed about 25%. Another indication of the extent to which hydrofining conditions are adjusted to secure a mild hydrofining operation is that the viscosity index of the oil is not increased above about 25 and is preferably increased to an extent less than about 20 points.

The process of the present invention may be more fully understood by the following example illustrating the same:

Example A lubricating 011 having the following inspections:

Inspections Feed Gravity, API 21. 9 Color, Tag Robinson 1% Flash F 4B0 Pour, F -10 Vis., Suybolt Seconds 915 Vis., 210 Saybolt Second 67. 5 V. L. 30.5 Conradson Carbon .07 Ncut. N0 1.3 R. I. at 20 C 1. 6065 Sulfur, Wt. Percent. 0.16 Grav. Spec .0242

was hydrofined using a catalyst comprising 0.1% platinum on alumina. The feed rates were one volume of lubricating oil per volume of catalyst per hour. The pressure utilized was 200 lbs. p. s. i. g. The results of these operations are as follows:

Operation 1 Operation 2 Inspections Hydro 500 Hydro 650 Grav. APP 21. 9 22.3 0010 T. 2% 9% Colorhold, T R.- 2 8% Fla 460 400 Pour, F 10 -10 Vis., 100 F. Saybolt Secon 913 645 Vls., 210 F. Saybolt Seconds- 67. 3 60. 4 V. I 40 48 Conradson Carbon.- .07 07 eut. N 1.06 0.10 R. I. at 20 C 1 5068 1.5065 Sulfur 0. 16 O. 12 Grav. Spec 9224 9200 From the above it is apparent that when mildly hydrofining the oil in accordance with the present invention, the color and the neutralization number of the product is materially bettered. It also is to be noted that the extent to which the viscosity index is increased is limited and the extent to which the sulfur is reduced is like wise limited.

What is claimed is:

1. The process of producing high quality lubricating oil of improved color and low neutralization number which comprises: treating a lubricating oil having a neutralization number above about 0.5 with hydrogen in contact with a catalyst consisting of about 0.05 to 1.0% of platinum supported on active alumina at controlled hydrogenation conditions selected from the range of 400-700 F., 50-250 p. s. i., and 0.5-5 volumes of liquid feed per volume of catalyst per hour, characterized by a hydrogen consumption of less than about standard cubic feet per barrel, a sulfur reduction which does not exceed about 37%, and an increase in viscosity index which does not exceed about 25.

2. The process defined by claim 1 in which said controlled hydrogenation conditions are characterized by a hydrogen consumption of less than 75 standard cubic feet per barrel, a sulfur reduction of less than about 25% and a viscosity index increase less than about 20.

3. The process defined by claim 1 in which the said lubricating oil is derived from a coastal type crude oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,542,471 Brandon Feb. 20, 1951 2,574,331 Knox Nov. 6, 1951 FOREIGN PATENTS 48 Australia 1. Aug. 2, 1929 27,680 Australia Jan. 12, 1931 

1. THE PROCESS OF PRODUCING HIGH QUALITY LUBRICATING OIL OF IMPROVED COLOR AND LOW NEUTRALIZATION NUMBER WHICH COMPRISES: TREATING A LUBRICATING OIL HAVING A NEUTRALIZATION NUMBER ABOVE ABOUT 0.5 WITH HYDROGEN IN CONTACT WITH A CATALYST CONSISTING OF ABOUT 0.05 TO 1.0% OF PLATINUM SUPPORTED ON ACTIVE ALUMINA AT CONTROLLED HYDROGENATION CONDITIONS SELECTED FROM THE RANGE OF 400-700* F., 50-250 P.S.I., AND 0.5-5 VOLUMES OF LIQUID FEED PER VOLUME OF CATALYST PER HOUR, CHARACTERIZED BY A HYDROGEN CONSUMPTION OF LESS THAN ABOUT 150 STANDARD CUBIC FEET PER BARREL, A SULFUR REDUCTION WHICH DOES NOT EXCEED ABOUT 